On rimfire guns, the firing pin strikes the rim or side of the back of the case. If there is no case in the chamber, the firing pin may strike the edge of the chamber which will damage the chamber and/or the firing pin. Not good.

Most center fire rifles are designed so that the firing pin will stop before piercing
the primer but it is still recommended that a snap cap or a fired case be used to minimize
wear to the firing pin.

In the case of rim fire guns It is "NOT" recommended because the firing pin can and does
strike the breach on the edge of the chamber and will upset the edge of the chamber eventually causing difficulty in chambering. (note; There are a few rim fire rifles that have a firing pin
stop to prevent this but as a rule most don't).

So my recommendation would be if you want to dry fire a center fire rifle or shotgun use a spent
case/shell or a snap cap. And don't dry fire a rim fire at all .

i've talked to several gunsmiths on the subject. the consensus is this: once upon a time materials used in both centerfire and especially rimfires where not as good as todays metals. this caused firing pins and other asscociated parts to be brittle and snap. according to them, there should be no problem, however using spent casings isn't a bad idea either to reduce the denting on the outer chamber.

they also said that the denting on the outer chamber from excessive dry firing tends to distort the chamber face causing the OAL of the cartiridge to change (as the rim thicknes of the cartridge basically sets how far in the cartridge goes) and causes small "gaps" around the rim which can cause accuracy problems.

there's no shortage of spent casings to use for the dryfiring is you feel uncomfortable doing it with nothing in there at all.

__________________
...that's what i like about toe tags; one size fits all...

Interesting thread!!!
I will be checking it frequently, to see the different opinions posted about it. I can learn something new out of it for sure. I dont dry fire my guns because I was tought that it is harmful for the firing pin, until now???

i have saved quite a few empties from my trips to the range and i didnt think you could have so much fun dry firing but..... i have been doing it scince i read the tip on using a spent case to save your chamber . i have "shot" about 500 squirrels and probably half that in crows and the cat that leaves paw prints all over my cars has theoretically ran out of its 9 lives about 15 times over.

When i did go to the range to let some real lead fly i found my trigger controll has improved so i would reccomend everyone at least grab a few spent shells and take em home, i dont know about everyone else but i live in the city and if i fired my gun the cops would be here in about 30 seconds, the cop shop is like 2 blocks from my house, but i can dry fire all i want without waking the neighbors,

I think it would be a good thing for even the most experienced shooter to do. no matter how long you've been shooting there is always something that you can do a little bit better. oh thanks to joaquin B for the tip on stuffing tissue paper in the case to stop crud from entering the barrel.

just to see what would happen i didnt plug one shell. and the amount of crap that flew into my barrel was surprising. it was about a pinch of fouling and wahtever else is in there(a pinch is a cooking term for those wondering. basically its about the amount of pepper that would come out of a shaker if you turned it over and back real quick. not alot on food but definatley bad for your

i have saved quite a few empties from my trips to the range and i didnt think you could have so much fun dry firing but..... i have been doing it scince i read the tip on using a spent case to save your chamber . i have "shot" about 500 squirrels and probably half that in crows and the cat that leaves paw prints all over my cars has theoretically ran out of its 9 lives about 15 times over.

When i did go to the range to let some real lead fly i found my trigger controll has improved so i would reccomend everyone at least grab a few spent shells and take em home, i dont know about everyone else but i live in the city and if i fired my gun the cops would be here in about 30 seconds, the cop shop is like 2 blocks from my house, but i can dry fire all i want without waking the neighbors,

I think it would be a good thing for even the most experienced shooter to do. no matter how long you've been shooting there is always something that you can do a little bit better. oh thanks to joaquin B for the tip on stuffing tissue paper in the case to stop crud from entering the barrel.

just to see what would happen i didnt plug one shell. and the amount of crap that flew into my barrel was surprising. it was about a pinch of fouling and wahtever else is in there(a pinch is a cooking term for those wondering. basically its about the amount of pepper that would come out of a shaker if you turned it over and back real quick. not alot on food but definatley bad for your

I totally agree with you on the use of spent rounds for practice.

When I was shooting High Power matches I loaded bullets (Only) in sized and spent primers (I
removed the primer punch pin from the sizing die) and practised getting into position,loading
the stripper clip and operating the bolt as I dry fired each cartridge and ejected them just as
I would in a match .While Also using my stop watch to help my timing.

It does help all aspects of shooting but be sure and use spent rounds if you are in your house
or as Savageman said you won't be very popular.

PS : I also used a red permanent marker to make sure they were easy to identify.